The present invention relates to molds for forming concrete pipe and, more particularly, to clamp mechanisms for locking the molds prior to a concrete pouring step and thereafter unlocking the molds to permit removal of hardened pipe.
In the fabrication of concrete pipes, a mold comprising spaced inner and outer mold forms is arranged in upright fashion. Concrete is poured into an annular chamber formed between the forms and allowed to harden. Thereafter, the outer mold form is opened, the inner mold is collapsed, and the hardened pipe is separated therefrom.
One type of outer mold form which is commonly utilized is of two-piece design, including a pair of semi-cylindrical sections which are secured together during pouring and later completely separated from one another to completely expose the hardened pipe for removal. These outer form sections are joinable together along two longitudinal mating edges, commonly referred to as "gates", which are tightly closed during the pouring step.
Locking connections between the outer form sections have been heretofore utilized in which manually securable clamps are attached between outwardly extending flanges of the form sections. Such clamps may include a series of bolts along each gate which are manually tightened to draw the flanges together into tight sealing relationship. Later, the bolts can be removed to allow the outer form sections to be taken apart. It will be realized that locking connections which require manual insertion, tightening and/or removal can involve considerable time and effort to manipulate.
Clamping systems have been previously proposed for outer mold forms in which a clamp linkage is fastened to both flanges at a gate, and a hand lever is connected to an eccentric shaft of the clamp linkage by means of which the flanges can be drawn tightly together or separated. In this regard, see U.S. Almquist Pat. No. 1,837,092 issued Dec. 15, 1931. However, devices of this type are not well suited to two-gate outer forms since the connection of the clamp linkage to both flanges precludes complete separation of the form sections. Moreover, the hand actuated linkage may become rusted or otherwise fouled and thus extremely difficult to actuate, requiring that it be subjected to the blows of a mallet.
The inner mold form is typically constructed of a cylindrical member which is divided along a longitudinally extending gate to define a pair of inner form portions whose outer edges are movable toward and away from one another. In order to remove the finished pipe, one inner form portion is collapsed within the other. Often this is accomplished by hammering a wedge between the hardened pipe and one form portion to deflect the edge thereof radially inwardly. This practice can involve considerable time and effort.
It is, therefore, an object of the present invention to minimize or obviate problems of the sort discussed above.
It is another object of the invention to provide novel locking mechanisms for inner and outer mold forms which are operable by remote control.
It is a further object of the invention to provide novel locking mechanisms for two-piece mold forms which do not require manual clamping efforts.
It is a further object of the invention to provide a novel locking mechanism for two-piece outer mold forms which is operated by a motor to clamp individual sections of the mold form together or completely release these sections from one another to permit removal of a pipe.
It is still another object of the present invention to provide a novel locking mechanism for an inner mold form which is operated by a motor to flex an edge of one form portion radially inwardly and then into the other form portion to effectively collapse the mold.
It is an additional object of the invention to provide novel mold locking mechanisms which are adapted for retrofit in existing concrete pipe molding units.